The density of the crane tube is the main variable that determines its characteristics. It is also an important link used to measure cleanliness and enhance the durability and rigidity of the machine.
1. Ethylene is the main raw material of polyethylene. A few other comonomers, such as 1-butene, 1-hexene or 1-octene, are also often used to improve polymer performance. For HDPE, the content of the above few monomers is average. No more than 1%-2%.
2. The addition of comonomer slightly reduces the crystallinity of the polymer. This change is generally measured by density, which has a linear relationship with crystallinity.
3. The general classification of the United States is in accordance with ASTM D1248, and the density of HDPE is above 0.940g/.C. The density range of MDPE is 0.926~0.940g/CC. Other classifications sometimes classify MDPE as HDPE or LLDPE.
4. Homopolymers have the highest density, the greatest stiffness, good permeability and the highest melting point, but generally have poor resistance to environmental stress cracking (ESCR).
5. ESCR is the ability of PE to resist cracking caused by mechanical or chemical stress.
(1) Higher density generally improves mechanical strength, such as tensile strength, stiffness and hardness.
(2) Thermal properties such as softening point temperature and heat distortion temperature.
(3) Anti-permeability, such as air permeability or water vapor permeability.
The lower density of the crane tube improves its impact strength and E-SCR. The polymer density is mainly affected by the addition of comonomers, but to a lesser extent by molecular weight. The high molecular weight percentage slightly reduces the density. This can effectively increase the service life of the Zeng Qianhe tube and increase the workload.
